OpenLink Virtuoso

From Semantic Web Standards

OpenLink Virtuoso

Name of the tool: OpenLink Virtuoso
Home page:
Date of latest release:
Programming language(s) that can be used with the tool: C, C++, Python, PHP, Java, Javascript, C#, ActionScript, Tcl, Perl, Ruby, Obj-C
Relevant semantic web technologies: RDF, RDFS, SPARQL, OWL, GRDDL, RDFa, RDB2RDF, R2RML, Direct Mapping
Categories: Triple Store, Reasoner, RDF Generator, SPARQL Endpoint, OWL Reasoner, RDFS Reasoner, RDB2RDF
See also:
Public mailing list:
Preferred project URI:
DOAP reference: VOS.rdf
Company or institution: OpenLink Software

(Tool description last modified on 2012-02-11.)


OpenLink Virtuoso is a SQL-ORDBMS and Web Application Server hybrid (aka Universal Sever) that provides SQL, XML, and RDF data management in a single multithreaded server process. Triple Store access is available via SPARQL, SIMILE Semantic Bank API, ODBC, GRDDL, JDBC, ADO.NET, XMLA, WebDAV, and Virtuoso/PL (SQL Stored Procedure Language). The product is available in Open Source and Commercial editions.

Virtouso is also an OWL Reasoner. In current versions, it supports owl:sameAs, rdfs:subClassOf, and rdfs:subPropertyOf, which are sufficient for many purposes. As of 5.00.3031, owl:sameAs, owl:equivalentClass, and owl:equivalentProperty are also considered when determining subclass or subproperty relations. As of 6.10, owl:TransitiveProperty, owl:SymmetricalProperty, and owl:inverseOf have also been added. Virtuoso defaults to using backward-chaining, but if desired, forward-chaining (i.e., materialized inferences) may be forced.

Virtuoso delivers RDB2RDF (formerly known as SQL2RDF) directly; via the Sponger and its cartridges, it can also deliver RDF from GRDDL, RDFa, microformats, and many more inputs.

Virtuoso includes a Live SPARQL Query Service Endpoint in all installations. A SPARQL-to-SQL gateway for locally-housed relational data is included in both Open-Source and Commercial Editions; Commercial Edition extends SPARQL Query distribution to any ODBC- or JDBC-accessible data source, SQL-DBMS or otherwise. Additional details and usage samples (including remoting/relaying to other SPARQL Query Services) are available. Commercial edition supports SPARQL-GEO as of Release 6.1.

DBpedia, Bio2RDF, the LOD Cloud Cache, and many other large data sets on the Web are currently hosted by Virtuoso instances.